Ribbon reversal mechanism



Apnl 28, 1959 E. A. DAMERAU ,1

RIBBON REVERSAL MECHANISM Filed July'S, 1957 INVENTOR. EDWARD A. DAME-RAH means of complex ribbon paths.

ribbons to undergo several direction reversals between United States Patent O RIBBON REVERSAL MECHANISM Edward A. Damerau, Pine Hill, N.J., assignor to Radio Corporation of America, a corporation of Delaware Application July 3, 1957, Serial No. 669,789 8 Claims. (Cl. 197-165) This invention relates to data processing equipment, and more particularly to business machines.

In machines with simple ribbon paths, such as type- Writers, ribbon reversal is accomplished through the use of a toggle switch arm which is tripped by a ribbon obstruction. When the obstruction reaches the switch arm, the wind-up reel continues to wind, the toggle is pulled, and the direction of the ribbon reverses.

In many present day business machines, a single inked ribbon can be used to produce many printed copies by It is not unusual for the supply reel and the take-up reel.

When ribbon paths become complex, however, the tensions and friction build-ups present a high order of resistance to such a simple reversal scheme, and the tension from the wind-up reel may be insuflicient to pull the toggle arm.

Accordingly, it is an object of the present invention to provide a simple, novel ribbon reversal mechanism.

It is a further object of invention to provide an improved ribbon reversal mechanism adapted for use with business machines utilizing complex ribbon paths.

It is a still further object of invention to provide an improved ribbon reversal mechanism that is operated at the take-up end of a ribbon.

It is a still further object of invention to provide an improved ribbon reversal mechanism less affected by the complexity of the ribbon path than prior ribbon reversal mechanisms.

It is an additional object of the present invention to provide a means to reverse a ribbon if tension in the ribbon exceeds a predetermined amount.

According to the present invention, a lever of the first class having two stable positions is mounted between the ribbon reels. At both reels, the ribbon is wound about a guide stud or the like on the lever, and then, in block and tackle fashion, the ribbon is looped through the aperture of a pair of fixed guide posts before being fed into the utilization area of the machine proper. The lever is coupled to a mechanism which alternatively drives the reels. An increase of tension at the reel being wound results in a multiplication of force through the block and tackle arrangement and the lever is toggled into its other stable position, changing the drive to the reels. The foregoing and other objects, the advantages and novel features of this invention, as well as the invention itself both as to its organization and mode of operation, may be best understood from the following description when read in connection with the accompanying drawing, iii which like reference numerals refer to like parts, and in which:

Figure 1 is a top view of a ribbon mechanism according to the present invention.

With reference to the figure, a machine is provided with an linked ribbon 10 which is wound on two reels 12, 14 which alternately function as supply and take-up reels.

It is to be understood that after the ribbon is exhausted from the supply reels, the functions reverse. For convenience, suppose the reel 12 now acts as the supply reel in Figure l. The path of the ribbon 10 passes between a fixed ribbon guide 16 at the supply reel 12 and through a similar ribbon guide 18 at the take-up reel 14.

A reversing lever 20 of the first class is positioned on the machine structure between the reels 12 and 14 on a fulcrum 0r pivot 22. The reversing lever 20 in this embodiment has the shape of a T with a yoke portion 24 at the base of the T and a lever bar as the cross-piece. The yoke portion 24 throws a reversing linkage 26, which is coupled to control a reversal mechanism which may be of the type commonly found on many business machines. The reversing lever 20 is provided with a bias spring 28, which connects to a toggle linkage 30. The spring-linkage combination 28, 30 gives the reversing lever 20 two stable positions, shown in the solid and dotted configurations.

Ribbon guide studs 32 and 34 are mounted respectively at the ends of the cross-bar portion of the T-shaped reversing lever 20. Two pairs of fixed ribbon guide posts 36, 38 and 40, 42 are mounted on the machine structure opposite the wide aperture guides 16 and 18 respectively. Each of the guide post pairs 36, 38 and 40, 42 is spaced apart to provide an aperture slightly wider than the thickness of the ribbon 10. The ribbon 10 extends from each guide post pair into the ribbon utilization area of the machine, as indicated.

As with most commercially available inked ribbons, the ribbon 10 has, at points near its ends, grommets 50, 52 or other obstructions which indicate the approach of the ribbon end. The guide post apertures are each too narrow to pass the grommets 50 or 52 which easily pass through the apertures of the guides 16, 18.

In operation, initially, the reversing lever 20 is in a stable position with a short ribbon loop between guide post 32 and the guide pair 36, 38 and a long loop between guide post 34 and guide pair 40, 42.

As the ribbon 10 is payed off from the supply reel 12 by tension transmitted through the ribbon 10 from the driven take-up reel 14, the grommet 50 reaches the guide post pair 36, 38 when the supply reel 12 is exhausted. There is, however, suflicient ribbon 10 remaining on the reel 12 at this time to provide for the loop between stud 32 and the guide pair 36, 38 when the lever assumes its then stable position.

As the take-up reel 14 continues to wind, and the ribbon 10 is held, either because of the obstruction 50 at the aperture of the guide pair 36, 38, or, perhaps, because of a stoppage or jam in the machine itself, tension builds up in the loop between the guide pair 40, 42 and the reel 14. Continued winding of the reel 14 shortens the loop between the pair 40, 42 and the guide stud 34, and the block and tackle action pulls the reversing lever 20 about the fulcrum of the pivot point 22 in a counterclockwise direction.

The lever 20 rotates until the spring and toggle 28, 30 reach a condition of unstable equilibrium and shift positions, biasing the lever 20 into the second stable position. Shifting of the lever 20 causes the yoke portion 24 to trip the reversing linkage 26, transferring the drive from the take-up reel 14 to the supply reel 12. The reversing lever 20, in its second stable position, provides a short ribbon loop between the guide post pair 40, 42 and the guide stud 34 and a long loop between the pair 36, 38 and the guide 32. As mentioned above, sufiicient ribbon 10 remains on the exhausted reel 12 to form the loop.

Under continued operation of the machine, the supply reel 12 now functions as a take-up reel and the take-up reel 14 functions as a supply reel until the ribbon 10 jams in the mechanism or the obstruction 52,.wound on the reel 14, causes the reversing arm 20 to rotate back to its original position, in a manner similar to that described above.

Thus, there has been disclosed a novel ribbon reversal mechanism which is not adversely afiected by tension build-ups along the ribbon path. A simple pulley arrangement cooperates with a lever arm biased as a toggle switch which switches when the ribbon cannot be fed to the take-up reel. Further, stoppages within the machine tend to cause successive reversals of the ribbon rather than increasing the ribbon tension which may cause damage to the ribbon, the ribbon guides, or driving mechanism.

What is claimed is:

1. In a ribbon feed mechanism having a pair of ribbon reels, the combination comprising a lever means having two stable positions and including a lever of the first class with a fulcrum between the ends of said lever, a first pair of guides on said lever respectively on each side of said fulcrum for guiding a ribbon along a ribbon path between said reels and a second pair of guides fixed with respect to said fulcrum for guiding said ribbon along said path between said first pair of guide means, whereby ribbon tension between the one of said reels acting as a take-up reel and that one guide of said second pair next adjacent said take-up reel in the ribbon path exerts a force on the one guide of said first pair between said take-up reel and said one guide of said second pair, which force is transmitted by said lever as a lever force tending to change said lever means to its other stable position.

2. In a ribbon feed mechanism having a pair of ribbon reels, the combination comprising a lever means having two stable positions and including a lever of the first class with a pivot between the ends of said lever, a first pair of guides on said lever respectively on each side of said pivot for guiding a ribbon along a ribbon path between said reels, and a second pair of guides fixed with respect to said pivot for guiding said ribbon along said path between said first pair of guide means, ribbon tension between one of said reels acting as a take-up reel and that one guide of said second pair next adjacent said take-up reel in the ribbon path exerting a force in block and tackle fashion on the one guide of said first pair between said take-up reel and said one guide of said second pair which force becomes a lever force tending to change said lever means to its other stable position.

3. In a ribbon feed mechanism, the combination comprising a lever means having two stable positions and including a lever of the first class with a fulcrum between the ends of said lever, a ribbon reversal mechanism responsive to the positions of said lever means, means to accommodate a pair of reels between which a ribbon extends, said means being connected to said ribbon reversal mechanism for causing one of said reels to act as a take-up reel and the other as a supply reel respectively according to the said positions of said lever means, and a pair of guide means on said lever respectively on each side of said fulcrum for guiding said ribbon between said reels, each of said guide means being so positioned in the ribbon path adjacent a corresponding reel that ribbon tension in said path between a reel acting as a take-up reel and its corresponding guide means exerts a force on said lever about said fulcrum tending to change said lever means to its other stable position and cause the other said reel to act as a take-up reel.

4. in a ribbon feed mechanism, the combination comprising a lever means having two stable positions and including a lever of the first class with a pivot between the ends of said lever, a ribbon reversal mechanism responsive to the positions of said lever means, means to accommodate a pair of reels between which a ribbon extends and connected to said ribbon reversal mechanism for causing one of said reels to act as a take-up reel and the other as a supply reel respectively accord- 4 ing to the said positions of said lever means, and a pair of guide means on said lever respectively on each side of said pivot for guiding said ribbon between said reels, each of said guide means being so positioned in the ribbon path adjacent a corresponding reel that ribbon tension in said path between a reel acting as a takeup reel and its corresponding guide means exerts a force in block and tackle fashion on said lever about said pivot tending to change said lever means to its other stable position and cause the other said reel to act as a take-up reel.

5. The combination with a business machine having ribbon reels and a ribbon, said ribbon having end warning obstructions afixed near each end, of a ribbon reversing mechanism comprising a rocker arm having two stable positions, a guide post mounted at each end of said arm, and a pair of guides mounted on said machine opposite each of said rocker arm guide posts, each said guide pair having an aperture through which said ribbon is threaded, said aperture being insufiicient to pass said ribbon obstruction, said guides providing a ribbon path extending from one of said reels, around one of said rocker arm guide posts, through the adjacent said guide pair aperture and through said machine to the other said guide pair aperture, around the other said rocker arm guide post and to the other said reel whereby the said obstructions from each of said ribbon ends alternately stalls ribbon travel and continued winding pulls said rocker arm in block and tackle fashion to assume the other stable arm position, said rocker arm being adapted to control a source of drive motion for alternative coupling to said reels for winding said ribbon.

6. The combination with a machine having a ribbon Wound on reels, of a ribbon controlled reversing mechanism comprising a pivot mounted on said machine, lever means of the first class rotatably mounted on said pivot, said lever means including bias means for providing two stable lever positions, a first guide stud, a second guide stud, said first guide stud being mounted on said lever means on one side of said pivot, said second guide stud being mounted on said lever means on another side of said pivot, first and second apertured guide members mounted on said machine opposite said guide studs respectively, whereby a ribbon path is provided around one of said guide studs through the corresponding apertured guide member and into said machine, and, from said machine through the other said apertured guide member and around the other said guide stud, such that ribbon tension at one of said apertured guide members is applied in said ribbon path to shift said lever means into the stable position tending to shorten the said path between the said corresponding guide stud and said one apertured guide member, and means responsive to said lever means stable position for reversably controlling the direction of motion of said ribbon.

7. The combination with a machine having a ribbon, ribbon winding means, and ribbon drive shifting means, of a ribbon controlled reversing mechanism adapted to operate said drive shifting means for reversing the direction of said ribbon winding means comprising a pivot mounted on said machine, lever means rotatably mounted on said pivot, said lever means having two stable positions, ribbon reversing means coupled to said drive shifting means and responsive to said lever means stable positions, a first guide, a second guide, said first guide being mounted on said lever means on one side of said pivot, said second guide being mounted on said lever means on another side of said pivot, and first and second aper-v tured members respectively mounted on said machine opposite said guides whereby a ribbon path is provided around one of said guides and through the corresponding said apertured member into said machine, and from said machine, through the other said apertured member, and around the other said guide, such that an increase in ribbon tension at one of said apertured members is applied in block and tackle fashion to said lever means for shifting said lever means into the stable position tending to shorten the path between the said corresponding guide and the last-mentioned said apertured member, whereby said lever responsive ribbon reversing means operates said drive shifting means to reverse said ribbon winding means.

8. The combination with a machine having a ribbon, of a ribbon controlled mechanism for reversing the direction of said ribbon comprising a pivot mounted on said machine, lever means rotatably mounted on said pivot, said lever means having two stable positions, ribbon drive means connected to be responsive to said lever means for controlling the direction of the motion of said ribbon, each ribbon motion direction corresponding to one of said lever means stable positions, a first guide, a second guide, said first guide being mounted on said lever means on one side of said pivot, said second guide being mounted on said lever means on another side of said pivot, and

first and second apertured members respectively mounted on said machine opposite said guides whereby a ribbon path is provided around one of said guides and through the corresponding said apertured member into the machine, and, from the machine, through the other said apertured member, and around the other said guide, such that increasing ribbon tension at one of said apertured members is applied in block and tackle fashion in said ribbon path for pulling said lever means into a different stable position, thereby reversing said ribbon drive direction corresponding to said lever position tending to relieve said ribbon tension.

References Cited in the file of this patent UNITED STATES PATENTS 

